Comparative Analysis of Three Severe Snowstorm in Nyalam

The weather process of three snowstorm events in the Nyalam on February 8th， 2012，February 16th， 2013 and March 11th，2017 was comprehensively analyzed using the NCEP/NCAR reanalysis data with resolution of 1°×1°、conventional meteorological data and FY2E satellite cloud images in this study， the elements of analysis include:System evolution， water vapor， thermal and dynamic conditions， etc.The results show that: （1） From the affected system point of view， the south branch trough of"2.08"and"2.16"Snowstorm Process developed a low pressure center，but the south branch trough of"3.11"Snowstorm Process was just only very deep.（2） The MPV1 of three processes in the Nyalam is positive， and it increases with height.MPV2 is negative above 500hPa and positive below 500hPa，all the values reach 4PVU.